1. Field of the Invention:
This invention relates to fuel nozzles for a jet engine and more particularly to an adjustable air blast nozzle to vary the air flow to the nozzle tip and to vary the fuel injection angle of atomized fuel as it exits the nozzle for burning in the engine combustor.
2. Description of the Prior Art:
In the prior art, a fuel manifold supplied fuel to a number of nozzles in the combustor of a jet engine. The nozzles normally were positioned generally symmetric about a center axis for generating a cone of atomized fuel which would be expelled from its nozzle tip. The nozzles were normally permanently mounted with the fuel manifold with the axis of symmetry of each nozzle parallel to one another with each nozzle generally spaced on a circular pattern at the upstream end of the combustor.
The design of a nozzle tip for providing atomized fuel has been the subject of extensive engineering design to provide complete burning of fuel during idling as well as under load. The nozzle tip, however, is positioned in fixed relationship with the nozzle body for expelling atomized fuel in a cone along the axis of symmetry of the nozzle and nozzle tip.
In U.S. Pat. No. 4,418,543, which issued on Dec. 6, 1983 to J. E. Faucher et al. a dual orifice fuel nozzle for the combustor of a gas turbine engine is described. A portion of air from the compressor is admitted internally in the nozzle through swirl slots positioned around an axis of symmetry of the nozzle and imparts a tangential velocity to the air as it progresses into the combustion zone along with the fuel which also rotates in the same direction. An outer annular ring of air only is formed by a swirl cup which imparts a targential velocity to the air by swirl vanes also positioned around the axis of symmetry of the nozzle tip.
In U.S. Pat. No. 4,139,157, which issued on Feb. 13, 1979 to H. C. Simmons, an air-blast nozzle having a primary and secondary fuel supply is described in which the primary fuel is spread into a thin cylindrical or conical sheet to be atomized by high velocity and/or high pressure air. The secondary fuel is also spread into a coaxial cylinder or conical sheet, of greater thickness than the primary, which combines with the primary sheet before being acted upon by the atomized air. The combined primary and secondary sheet of fuel provide a single spray of constant shape at all operating conditions. Inner and outer air flows, which may be swirled, provide high velocity air streams which converge on the fuel sheet downstream to cause breakup of the sheet of fuel and the production of an atomized spray.
In U.S. Pat. No. 4,362,022, which issued on Dec. 7, 1982 to J. E. Faucher et al. a dual orifice nozzle is described with means for preventing coke buildup in the secondary fuel passage. The air pressure is increased in the secondary passage at times the secondary passage of the dual orifice is in the inoperative mode and the primary fuel passage is in the operative mode.